Automatic telephone system



Aug. 4, 1925 1,548,679

G. GRABE AUTOMATIC TELEPHONE SYSTEM Filed Dec. 1.8. 1922 2 Sheets-Sheet 1 Q Q Q Inuen [II-- E015 E1573 Aug. '4, 1925. 1,548,679

G. GRABE M-JTOMATIC TELEPHONE SYSTEM Filed Dec. 18. 19 2 Sheets-Sheet 2 I 5% Brake Patented Aug. 4, 1925..

a inc GEORG GRABE, 0:? NIKOLASSEE, NEAR BER-LIN, GERMANY, ASSIGNOR TO SIEMENS 85 HALSKE AKTIENGESELLSCHAFT, OF WERNER/WEEK, SIEMENSSTADT, NEAR, BER- LIN, GERMANY.

AUTOMATIC TELEIHONE SYSTEM.

Application filed December 18, 1922. Serial No. 607,471.

T 0 all whom it may concern:

Be it known that I, Gnone GRABE,a Ger man citizen, and a resident of 17 Sudenstn, Nikolassee, near Berlin, Germany, have invented certain new and useful Improvements in Automatic Telephone Systems, of which the following is a specification.

The present invention relates to circuit arrangements for telephone systems with automatic working, in which numerical switches e. g., group selectors) have access to large groups of lines, wherein current impulses occur when a large number of intermediate switches, that are standing on engaged lines, are moved on, these impulses having a deleterious effect on the battery.

Now the object of the present invention is to avoid this deleterious effect on the battery, this being achieved'by moving on in groups the intermediate switches standing on engaged lines.

This general solution of the invention is effected in that the movement of the intermediate switches is controlled over a special switching device, which is dependent on switching means at the intermediate switches.

The drawing shows in a simple diagrammatic manner one method of carrying out the invention. In Figure 1 the calling subscriber is marked A, hecan reach a group selector D over a line switch C. Figure 2 shows a continuation of Figure 1, in it E designates an intermediate switch accessible by a group selector D, designates a switching device (stepping switch, auxiliary switch) which is common to the intermediate switches, and F designates a group selector located beyond the intermediate switch.

The method of operating an installation according to the invention will now be described. When the subscriber A takes down his receiver the circuit for the line relay 2 of the line switch C is closed. The relay 2 is energized and at its lower contact closes a circuit for the switching relay 3 and the rotary magnet l of the line switch C. As is indicated by the solid black upper portion of relay 2, the copper slug by means of which this relay is made slow acting is placed on the armature end of the relay and therefore prevents the armature from becoming attracted until the core of the relay has become sufiiciently saturated to enable it to holdup asufliciently long interval after the-circuit is subsequently opened by relay 3, as pointed hereinafter (the usual position of the copper slug on the heel end of slow acting relays, such as 9 and 10 of switch D, being indicated by a shaded portion at the lower end of their respective cores). If the wipers of the line switch 0 rest on an engaged line leading to a group selector, earth potential is connected to the test Wiper 5, whereby the relay 3 is short circuited and the rotary magnet & receives the full pressure, so that it operates and rotates the wipers 5, 6 and 7. As soon as a free line is found the relay 3 is energized. It operates its' contacts and at its upper and lower contacts opens the circuit for the relay 2. The calling subscribers line is now connected with the group selector D, whereby the circuit is closedfor the relay 8. The relay 8, at its contact connects up the slow releasing relay 9, which connects up at its upper contact 20 earth potential to the test wiper 5, thus marking the line engaged, and at its lower contact prepares the circuit for the relay l0 and the lifting magnet 11 of the group selector D. The calling subscriber now operates his number dial and thus transmits a train of impulses corresponding to the first digit of the wanted subscribers number. The relay 8 is de-energized a number of times corresponding to the train of impulses, and at its contact repeats the impulses to the relay 10 and lifting magnet 11, the circuit of which was prepared at the lower contact of relay 9. The relay 10 remains energized during the impulse transmission and during this time maintains energized the following circuit: earth, contact 20 of the relay 9, contacts 12 and 13 of the relay 10, off-normal contact l l (closed at the first lifting step), winding of relay 15, battery, earth.

he relay 15 at its contact 16 prepares a circuit for the rotary magnet 17 of the group selector D, and locks itself over its contact 18 and the contact 19 of the rotary magnet 17. The relay 10 is de-energized at the end of the train of impulses, closes its contacts 12-21 in the circuit prepared for the rotary magnet 17: earth, contact 20 of the relay 9, contact 12-21 of the relay 10, contact 16 of the relay 15, winding of the rotary magnet 17, battery, earth. The rotary magnet 17 moves on the wipers one 7 step, andat its contact 19 opens the circuit iii for the relay 15, which is tie-energized, and by opening its contact 16, interrupts the circuit of the rotary magnet. Thetest wiper '21: now IHOVBSOIL .to thentest contact of the first trunk line leading to an intermediary switch E. The rotary magnet 17 is deenergized and has again closed its contact 19 so that the following circuitfor relay,

is established: earth, battery, winding of the relay 15,, off normalcontact 14-, Contac 19, of, the rotary magnet 17, contact 22 -23 is, energized and at its contact 16 again closes the circuit for the rotarymagnet l7, whereby the wipers ofthe groupseleetor D are lTl Olt ClnOll ,onecontact, and are thus switched on to the next trunk line leading to-an interinediary switch- This swit hing operation isc repeateda ntil free intermediary switch E is found, whichhas beenset on-a tree trunk, line ,leadingto, a second group selector, F; K j l Assumin that such an intermediary switcl ,E', setpn a ,tree trunk line, has, been 1 round at the test contact 24, then a circuit is closed for the switchingrelay 26;: earth,

contact, 3f the relay 9,. winding of, the relay 26; Contact .19.,of therotary magnet 17,

oitnorinalrontact 1e1 winding of the relay 15,. battery,;-earth The relay 15 cannot, be p energi -p'ed ,in th s ,CHCull because the. relay 26,,has' a ,hrgh olirnicresistallce ,Therelay 26', WhlQ liQhQ- its, contacts, has switched through the connection 1 as far as thefllntei mediary swltch E, ca'nnotoperate before the ,shortecircuitr hasbeen removed train its 1 winding (this has been set up by the potential eartl1, which has been, e'xtendedhhaol; through the test wipers of the engaged interinedi'ary switches Similar to E) The1opcrationpf relay -26 connects, earth potent al automatically to ,the testiwipergffil,

whereby the following circuit is closed: earth, contact 20-v of the; relay 9,, closed front contact-23 of the relay 26 test wiperfll and contact of the rgroup selector-,1), lead 25, low res stance winding of; relay 30, winding of ,the relay, battery, earth.[( A second high resistance windii g ,of,-relay 3Qisconnected, in parallel 'to this circuit over the high resistance-36, The windings of, relay Scar So .c0nnecte l that they assist one. an-

other The, relay 30 ;at its contactsS'Z and 38 connects thronghithe speaking leads, whereby ,a circuit is,fclo sed for the impulse N relay 44 of the succeeding group selector F.

in their operated position. vlector I isnow operatedn the samenianner Furthermorethe relay 30 connectsiitself at contact 39 in the following circuit: earth, contact 20 of the relay 9, contact 23 of the relay 26, .wiper 21 and contact 24, lead25, its owncontacts 40., alwand 39,,ihighiresistance winding of the relay, 30, battery,,earth,

and the relay 33 is now connected up over contacts lO-and 1.1 of relay 230, battery, earth. As soon as the impulse relay 44 operates it connects up the releasing relay 42. The latter at contact 43 connects earth to the releaselc'adand wiper 35, whereby the relays 30 and 33 are jmaintained energized and thus the switches G and, D are maintained The group seas the group selector D; H

11; a number of intermediary switches E are engaged and the free intermediary switches stand on engaged lines leading to v succeediiw' oup selectors, the relays33wand V r :54; lfltllVl-(llltll to separate intermediary selectors are energ zed by earth potential on thetestlead 25 and ,on the wiper 35.; Thereb the Clifilllh extending over the serially connected contacts of these relays is closed for -the common starting relay 32;; This closesat ts contact 63the;circu it, for the rotary magnet L5. of the stepping switch TV which is 111 the normal posit on: earth, contact 63 of the relay 32, bank contact 52'and wiper 46 of the steppin r switch lfwinding of the rotary magnet 4:5,[self interrupter .62, battery, earth. The rotary magnet 45 is energized inf this circuit and causes the wipers 46' and i8 ot' the stepping switch to leave their normal pos t on and to move on to the @first contact. If it is assuinedj that the intermediary switch E-{is free, but its outgo ng trunh hncs are engagedpthe followingci'rcuit ,for the rotary magnets of :the l first group of intermediary switches is closed over the first contact Sh and t-he wiper 4C8, as ,911 as the wipers 16' and i8 are set on their first cont-acts earth, battery, winding ofthe relayei, wiper g8 and contact 54,,selt

interrupter and, winding of the rotary ni'agnot 31, back contact ll of the relay 30, wiper 35,'banl; contact, on which the intern' ediary Y switchjstands, testilead of the engaged line, earth. The slow act ng relay 4:7,"lo1cated in this circuit, energized. and opens its contact 5-1,- ,whereby the new: circuit for the .rotary magnet if of the steppingswitch his openedj; Hence the wipers of the step )ing switch W remain in the position 1. I all the free intermediary switches ofthis group have reached a tree trunk line, there is no earth potential on the test lead. The motor magnets 31, and the slow acting relay 47,. in

,thejmotor magnet circuit are therefore deenergized, The relay. 47 again closes its contact 64,.so thatthe circuit of the rotary magnet d5 of the stepping switchWV ,is, established: earth, contact 61" of the relay 59,'back contact 64 of the relay 47, bank contact and wiper 46, rotary magnet 45, self interrupter 62, battery, earth. The rotary m'agnet 45 operates and moves the wipers 46 and 48 on to the second contacts 66 and 67. Thereby the motor magnets of the second group of intermediary switches are connected up over the wiper 48, contact 67 and the lead 49, it being understood, of course, that the switches similar to E under the control of whose test wipers the circuit of relay 32 is initially completed have been arbitrarily divided into groups as regards the circuits of their motor magnets. circuit the relay 47 again operates, so that the circuit for the rotary magnet 45 of the stepping switch is opened. The stepping switch IV is stopped. The free intermediary switches of the second group, which are standing on engaged lines are set on free lines in the manner before described. When this has been efi'ected the relay 47 is deenergized, it closes its contact and thereby again establishes the circuit for the rotary magnet 45 of the stepping switch W. The wipers 46 and 48 of the stepping switch are set on the third contacts 68 and 69. The stepping switch W is again stopped, the motor magnets of the free intermediary switches accessible over the line 51 obtain current and set themselves on a free line in the manner described. This operation is repeated until all free intermediary switches in the several groups have been set on treelines, or until the stepping switch IV has made a complete revolution and has returned to its normal position. IVhen the wipers 46 and 48 reach their normal position the circuit extending over the bank contact 52 and wiper 46 to the rotary magnet 45 of the stepping switch IV is opened, since the relays 33 and 34 individual to separate intermediary switches E have deenergized because the associated switches have stepped to idle contacts-and have opened the circuit for the common starting relay 32 so that the latter opens the circuit of the rotary magnet and stops the stepping switch IV.

If all the intermediary switches E or all the lines leading from the intermediary switches to the succeeding group selectors are engaged, the switching relays 58 at the succeeding group selectors have been ener gized in known manner and have opened their contacts 53, or 55, 56, 57, whereby a short circuit is removed from the relay 59 associated with the stepping switch, so that it is energized over: earth, winding of the relay 59, resistance 60, battery, earth. The relay 59 opens its contact 61 and thus interrupts the circuit for the motor magnet 45 of the stepping switch WV. Thereby the continuous rotation of the wipers of the step In this ping switch IV is prevented if all the lines leading to succeeding group selectors are engaged.

lVhat I claim and desire to protect by Letters Patent is 1. In a telephone system, a plurality of automatic trunk hunting switches divided into groups, and means common to said switches for advancing the idle ones from busy trunks to idle trunks, one group at a time.

2. In a telephone system, a plurality of automatic. trunk hunting switches, means common to said plurality of switches and normally ineffective for bringing all the idle ones of said switches into engagement with idle trunks, .means for rendering the last named means effective, and other means for maintaining the last named means eiiective until all the idle ones of said plurality of switches have been set upon idle trunks.

3. In a telephone system, a plurality of automatic trunk hunting switches each having a test wiper, said switches being divided into groups, a motor magnet in each switch having one terminal normally connected to the associated test wiper, the other terminals of said magnets being normally disconnected, means for connecting a source of current to said test wipers when the trunks on which said wipers are standing become busy, and means including a relay common to all said switches for connecting the normally disconnected terminals of said magnet to said source of current to cause said switches to hunt for idle trunks, the last named means being arranged so that the magnets of one group only are connected up at any given instant.

4. I11 a telephone system, non-numerical switches, trunk lines accessible in common to said switches, wipers for said switches normally standing on a plurality of said trunk lines, and means controlled in accord ance with the busy or idle condition of the trunk lines upon which said wipers are standing for causing the idle ones of said switches to automatically rotate in succession in search of idle trunks.

5. In a telephone system, a plurality of non-nun'ierical trunk hunting switches divided into groups, a starting switch for starting said non-numerical switches one group at a time, and an operating circuit for said starting switch controlled jointly by means individual to said non-numerical switches and by means individual to the trunks accessible thereto.

Signed by me this 11th day of December,

GEORG GRABE. In the presence 0f F. LUHBERGER, A. KNrrsoHER. 

